1. Field of the Invention
The present application relates to a drilling fluid composition and method of use thereof in drilling subterranean wells. More particularly, the application relates to such a fluid which is flowable but non-liquid, i.e., is dry.
2. Description of the Prior Art
In drilling wells in the earth it has long been the practice to employ a drill bit or similar device to drill a bore hole and to circulate past the drilling apparatus a drilling fluid to cool the drilling apparatus, lift cuttings out of the hole, and counterbalance the subterranean formation pressure encountered. A wide variety of drilling fluids have been used including aqueous base liquids, hydrocarbon base liquids, air or other gases, mists, foams, and the like. For many drilling applications, present-day drilling fluids are inadequate. For example, in some instances it is desirable to use a drilling fluid low in density. If a drilling fluid having the density of an aqueous liquid or a hydrocarbon base liquid is used, some formations being drilled are so friable and fragile that they will undesirably fracture under the weight of the column of drilling fluid. This can result in loss of the column of drilling fluid to the formation, loss of circulation, and disruption of the drilling operation. Known lighter density drilling fluids such as air, mist and foams are often too compressible, unstable, or have too high a fluid loss to be entirely acceptable. In other instances, especially in drilling wells which will produce gas, known drilling fluids often tend to at least partially penetrate the formation during drilling resulting in plugging of a sharp reduction in permeability of the formation through which the formation fluids will eventually be withdrawn. Thus, there is needed a low density, stable drilling fluid with a low fluid loss which causes a minimum of formation damage.